Directional drilling is a well established art in the well drilling industry. Various elements are available for inclusion in the drill string to influence the course of the well bore as drilling progresses. Apparatus for use down hole to indicate at the surface various parameters measured down hole are now in common use and are generally known as Measurement While Drilling or MWD arrangements. At the present time the drill string has to be rotationally oriented relative to earth to measure and influence the course of the well bore as it is further drilled.
With frequent down hole measurements now readily obtainable, small deflections of the axis in the down hole assembly can usually accomplish all changes required during a normal bit run. Bent subs with axial deflections in the range of three degrees are quite common. The small deflections permit the drill string to be rotated without overstressing the string in the vicinity of the bent sub provided the bent sub is of robust construction.
There are two salient problems in making up the down hole assembly to drill with directional control with bent elements. The first problem pertains to rotational alignment of drill string components separated by threaded connections. The second problem pertains to adjustably bending the bent sub to deflect the centerline of the lower portion of the string relative to the upper portion. Apparatus of this invention addresses both problems with almost identical constructions.
It is therefore an object of this invention to provide an adjustable orienting sub to change the relative rotational orientation of axially spaced portions of the drill string.
It is another object of this invention to provide an adjustable bent sub to select the amount and secure the selected deflection of the drill string centerline.
It is yet another object to provide adjustable orienting subs that require no shims and may complete the adjustment by application of torque in the manner used on tool joints and with the same tongs.
It is still another object of this improvement to provide visible, manually controllable, features for all elements of the sub to be manipulated during adjustment and torque application.
It is yet a further object of this invention to provide the adjustable sub usable in a drilling motor body to change, at least, the axial deflection between upper and lower tool joints of the motor.
These and other features and advantages will be apparent to those skilled in the related art from consideration of the included claims and appended drawings.